Carb main jet et2
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Member
Custom vespa et2
Joined: 31 May 2019
Posts: 8
Location: Wicklow, Ireland
Tue Jun 11, 2019 12:53 am quote
Hey guys, just bought a new 17.5mm carb for my et2 has been parked up for years and seals were gone on the old 12mm carb, I have the new carb in and have a red malossi air filter in the box with the snorkel removed. I don't know what size main jet came in the carb as it wasn't marked. I have steadily gone up in size till I was at an 88 main jet and with the air mixture screw all the way in the bike is still running a little lean. Am I missing something? Has a Leo vinci pipe. Thanks
Molto Verboso
lx 50
Joined: 09 Oct 2017
Posts: 1032
Location: Brighton
Tue Jun 11, 2019 2:32 am quote
Put the air box fully back on with the stock filter mate.

You do not need the red, not even nearly.

Then youíll probably start winding stuff back and lowering your main jet.
Enthusiast
ET2 2004
Joined: 27 Oct 2018
Posts: 70
Location: UK
Tue Jun 11, 2019 6:50 am quote
As Bill says I'd just go with the standard black filter and closed airbox. From memory mines got a 62 main jet and the standard type filter, the plug is a good colour and it does high 40's mph on the speedo (so low 40's in reality then...). It ran like absolute crap a few weeks ago and all it was was the airbox wasn't quite snapped shut properly

Cheers
Rich
Hooked
GTS 250ie Super, Italjet Velocifero, Scarabeo 150, S50,ET4
Joined: 22 Nov 2016
Posts: 413
Location: Winston-Salem, NC
Thu Jun 13, 2019 5:56 pm quote
How do you know it's lean? Is it only lean at WOT or idle and mid throttle?
Your air/fuel screw is only for the idle, if it's all the way in then your pilot jet is too big. This has nothing to do with being lean for much above idle but is still a problem. 88 sounds like a good place to start if it's to lean go to 90. I would get the pilot jet sorted out then go to the needle and slide for mid range then worry about the main jet.
Molto Verboso
lx 50
Joined: 09 Oct 2017
Posts: 1032
Location: Brighton
Thu Jun 13, 2019 9:52 pm quote
This is just a thought.

The LX50 2 stroke, stock had in its earlier years a 57 main jet, then on later models it went up to 63.

What is actually different between the ET2 and LX50 2T?

My LX then had a 70cc head, performance exhaust, variator....the works, and I was still under a 70 main jet from memory.

If there fundamental differences then discount everything Iíve said, but if they are the same 88 seems way too high.
Hooked
64 Allstate, 05 ET2, 09 GTS
Joined: 17 Apr 2016
Posts: 260
Location: Portland, OR
Sat Jun 29, 2019 8:37 pm quote
Re: Carb main jet et2
Wasp2s wrote:
I have steadily gone up in size till I was at an 88 main jet and with the air mixture screw all the way in the bike is still running a little lean.
If your bike runs with the air mixture screw turned fulled closed, you have an air leak. You cannot accurately jet until you fix the air leak.

Spray WD-40 around the carb fittings, one at a time, while idling. If the bike races, that spot is your air leak.

For reference, people with a 70cc kit and aftermarket exhaust seem to run 80-88 main jets on 17.5 PHVA carbs, with 85 being the most common end point. If youíve got a stock 50cc and stock pipe, an 88 main jet on a 17.5 PHVA carb seems way too big. An air leak would explain it.

Good luck, these are super fun bikes and a bigger carb is a smart idea! A 12mm carb is silly small, Vespa must have used such a small carb for emissions purposes. My Tomos moped has a bigger carb. Stock, 14mm PHVA.

A825F37D-917A-40BA-927D-1069E5E59BF1.jpeg

Member
Custom vespa et2
Joined: 31 May 2019
Posts: 8
Location: Wicklow, Ireland
Tue Jul 02, 2019 2:33 pm quote
Thanks so much guys, 17.5 mm carb 85 jet malossi red sponge filter in stock box, lighter rollers stiffer springs in clutch, Leo vinci touring exhaust derestricted, baffle removed. bike is running great, still feels like it wants to go faster but is doing 72kph on flats. Deffinatly thinking of putting the 70cc malossi cast iron kit on next.
Will post some pics soon, have brown gv leather dual seat with lx rear brake light and aftermarket lx back carrier, with grab handles. So great full for all the help,
Hooked
2008 GTS250, 2009 S150, 2017 GTS300Super, 2006 GT200
Joined: 18 Oct 2014
Posts: 213
Location: Houston
Tue Jul 02, 2019 8:48 pm quote
Siggy Javotnik wrote:
For reference, people with a 70cc kit and aftermarket exhaust seem to run 80-88 main jets on 17.5 PHVA carbs, with 85 being the most common end point. If youíve got a stock 50cc and stock pipe, an 88 main jet on a 17.5 PHVA carb seems way too big.
What about an ET2 with a 70cc kit, 19mm PHBG, Leo Vince Touring (derestricted), stock airbox with the 3 holes Malossi instructed to drill and a red Malossi filter? Bike has good throttle response for the first 1/8 throttle, feels and sounds like itís getting too much gas through the midrange, and is strong WOT. Iím running a 90 jet now.

On another note, just tried to do my first plug chop, made it about 2 miles WOT and the bike just suddenly died like it wasnít getting gas. Had to push it home, gave up trying to start it and two days later it started at the first push of the button. Iíve tried to troubleshoot it, could it possibly have been starved for fuel since I didnít swap out the gas cap like it I was instructed to do in the carb manual?
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